Chain grate



A. G. FOX.

CHMN GRATE.

APPLICATlON FILED APR.26, 19H.

Patented Aug. 9, 1921..

Qqiforney UNHTQ STATi'EEii PATENT CHAIN GRATE.

Specification of Letters latent.

Patented Aug. 9, 1921.

Application filed April 23, 1917. Serial No. 164,708.

T 0 all whom it may concern:

Be it known that I, ALFRED Gnonen F ox, a subject of the King of Great Britain, residing at 87 Erlanger road, New Cross in the county of Kent, England, have invented certain new and useful Improvements in Chain Grates, of which the following is a specification.

This invention relates to automatic stokers of the type in which burning fuel is fed from the front to the rear of the furnace by movement of the grate, for example by a power driven continuous chain grate. In conjunction with such grates it is usual to employ a number of dumper bars, or ash plates, pivoted about a fixed beam or bearer bar and extending across the rear end of the grate which serve to divert the clinker and ash into a storage hopper or ash pit from which it may be Withdrawn at intervals throughsuitable dampers; at the same time the dumper bars preserve an effective air seal to the furnace.

It is essential for eflicient utilization of the fuel that no unburned fuel passes over to the hopper and also that the burning fuel should properly cover the whole of the grate up to the dumper bars in order to prevent air leakage through the rate, and consequent lowering V of the efficiency of the boiler. It is equally or even more important that the ash and clinker shall not effect a lodgment, beyond a limited extent, and accumulate at the dumper bars, but shall continue freely to pass over them and discharge into the storage hopper.

This invention consists in providing dumper bars mounted indirectly through pivoted supporting bodies upon bearer bars which are adjustable along a path such that the ash receiving face of the dumper bar may be moved between position substantially above and below the upper grate level and will form a practically air-tight sea] therewith in all positions, while a second practically air-tight seal is formed by the aforesaid supporting bodies engaging with a stationary member such as a fixed plate. The invention further consists in improvements in the construction and arrangement of the various parts so that the renewal of parts can be readily effected and the possibility of jamming during working or of the dumper bars being pushed back is avoided The adjastment of the dumper bars may be hand controlled and discontinuous, or automatic and continuous, according to the class of fuel being burned. I have found that by the use of such adjustable bars more uniformly efficient results may be obtained from a boiler with different classes of fuel than has been possible hitherto.

In carrying this invention into effect I pivotally support the lower ends of the dumper bars (which may be separate or in sections) on pivoted members mounted on a movable bearer bar which extends across the furnace so that the upper ends of the dumper bars make a sliding practically airtight joint with the rear end of the grate while the pivoted members which are the direct support of the dumper barsmake a similar joint with the side or bottom of the ash-pit in which the ash and clinker is collected. The bearer bar may be moved up and down for adjustment of the position of the noses of the dumper bars by rack and pinion mechanism or by eccentrics on a shaft extending through the furnace wall beneath the grate or by, other suitable well-known mechanism for enabling the adjustment to be made from the outside of the boiler furnace.

The movable bearer bar carrying the dumper bars may be connected to one arm of a pivoted lever or levers under the grate or on the rear axle of the grate, the other arm of this lever being fitted with a counterbalance weight so as to enable the bar'to be easily moved by the actuating mechanism.

The invention will be better understood by reference to the accompanying drawings in which Figures 1 and 2 represent elevation and plan respectively of portions of a grate constructed according to my invention.

In the drawings, (t represents the rear end ofa chain grate, the rear axle of which is generally made adjustable longitudinally of the grate to accommodate for changes in the length of the grate due to expansion, wear of the link holes and link rods or other causes. These links generally form a series of flats or chords as they pass over the guide wheels at the ends of the grate. The dumper bars b bear against the rear end of the grate and are pivotally su ported indirectly on an adjustablebearer ar 0 through a plate or body portion (Z which may be tontinuou's across the width of are grate fuel being I consumed.

but whixh I prefer to make in a number of seotlons.

to prevent them from being thrown off their This is complished by providingthe bearer bar or supporting member with an upwardly projecting portion 8 whi'h is substantially f-shaped in cross section and forming a corresponding V-shaped groove bearing portion tin the lower portion of the dumper bar. The sides of the V-shaped groove embrace a sli htly largerangle than sides of;

the bearer bar so that the dumper bar may have a certain movement. As shown both the bearer bar and the groove in the dumper bar may have flattened engaging portions.

In some cases a fixed stop may be provided to prevent the dumper bars from bemoved too far from the grate. plate d, whether made continuous or of a number of sections, is also pivotally suspended from the bearer bar 0 and the center of support of bar I) is so arranged that the lower edge of the plate d is held by gravity, no matter what the position of the bar 0 is,

against a plate 6 secured to or forming the,

bottom or aside of the ash pit-so as to make Et COl'ltlIlLlOllS and practically air-tight seal therewith. The door: 9 through which,

the clinker and ash are withdrawn may bear against the lower side of the platee, as shown in the drawing. The dumper bars 6 makea second substantially air-tight seal with the end ofthe grate. The bearer bar '0 is adjustable along the arcuate path which is concentric with the. rear axleof the grate so as to arrange that the noses of;

the 'dumper bars bear against the portion of the grate most suitable for the type of The bar e is constrained to the path 0cy by a slotted mem- Q61 q at each end of the bar.

v The adjustingmechanism forms no part of the present invention but may be of any well-known or suitable type and may be power driven or operated by hand-f The mechanism shown is merely an example.

The. upper or working ends of the dumper bars I) are preferably made renewable as has hitherto been proposed by being dovetailed onto the major portiomas shown, and I may also form theupper surface with slots or perforationsbf for the admission of air and to allow of thebetter combustion of fuel and cooling of clinker lying against the bar as has also been proposed. r This construction and mounting of dumper bars and pivoted supporting body above described and illustrated in Figs. ,1 and 2 I have-found in practice to be a very satisfactory form. of the im'ention, afiord.

The pivotal mounting of the dumper bars is such that they have only a limited movement away from the grate so as The ing as it does the following, among other,

advantages (1) Absence of jamming; considerable elasticity, adjustment of the rear shaft and stretching of the grate, etc, or other relative movement between grate and ash pit wall, being permissible by reason of the interplay of dumper and supporting bars' (2) Wide angular rotation of the 'ash receiving face between banking and clearing positions, rendering the system adaptable to fuels having widely different burn ing characteristics. 1

(3) Quick and ready renewal of burned or otherwise defective parts of the dumper or supporting bars owing to their not being bolted or threaded ona shaft. r 1

(a) Pushing or rocking back of the dumper bars, (a common trouble) avoided; limited clearing movement only being allowed. a r

(5) Complete and constant air sealing in all positions.

(6) when the noses of the dumper bars shorten by burning each individual bar ,adjusts itself automatically to the grate so that the seal is kept continuous. V I

What I claim as-new and desiretosecure by Letters Patent of the United States, is

1. In combination with a furnace having .a traveling grate, dumperfbars forming an air seal with the grate, supportingmeans for said bars comprising; a shaft and bar-v adapted to be adjusted to -position the dumper bars either above or below thesgrate surface, a fixed member, and interplaygdej vices adapted to form an a1r fixed member.

2. Thecombination with a-furnace having a travellng grate, of dumper bars forming seal with the j I an air sealwith the grate, supporting means 7 for said bars comprising a shaft adjustable parallel to itself and bar-supporting mem; hers between said adjustable shaft and said bars, said bar-supportingv means being adapted to be adjustedto position the dumper bars eitherabove orbelow the grate surface, a fixed member,jjanda ir sealing device adaptedto maintain a seal with the fixed member;

8. In combination witha furnacehavin'g a traveling grate, a fixed -member,-ja shaft adjustable parallel to .itself, bar-supporting members on the shaft, interplay extensions on the supporting members forming an air seal with the fixed -member, dumper bars pivotally mounted onthe bar-supportin members and adapted-to mainta-in anjair seal with the grate, the adjustment of the shaft being adapted to position the dumper bars above-or-b elow the grates urface. 1

4%. The combinationwith a furnace having a traveling grate, of a fixed. member, a shaft,

bar-supporting members removably supported on the shaft and having integral extensions adapted to form an air seal with the fixed member, dumper bars removably supported on the bar supporting members, and forming an air seal with the grate, the shaft being adjustable parallel to itself to position the dumper bars above or below the grate surface.

5. The combination with a furnace having a traveling grate, of a fixed member, a shaft adjustable parallel to itself, members seated on the shaft, each of said members comprising a shoulder and a relatively long extension, said member being so proportioned that the extensions are positioned by gravity in contact with the fixed member in all positions of the shaft, dumper bars seated on the shoulder of each member and being so proportioned that one edge thereof is positioned by gravity against the grate surface in all positions of the shaft, the shaft being adapted to position the dumper bar above or below the surface of the grate.

In witness whereof, I have hereunto set my hand this 11th day of April, 1917.

I ALFRED GEORGE FOX.

Witnesses:

CHARLES H. BURGESS,

PHYLLIS M. IVORY. 

